Amphiphilicity of polymer surfaces play an important role in biocompatibility. However, the conception of the balance between hydrophilicity and hydrophobicity remained to be obscure owing to the lack of systematic research on biomedical application of amphiphilic polymers. We have synthesized 2-hydroxyethyl methacrylate-styrene block copolymers to control the amphiphilicity in the level of assembled order of macromolecules. Interaction of platelet with the block copolymer surface precoated with or without blood proteins was investigated by the microsphere column beads method to clarify the mechanism of the antithrombogenic properties of microphase separated structure. Block copolymer surface exhibited antithrombogenecity due to the blocking platelet adhesion and aggregation. It was considered that the organized structure of adsorbed proteins on the surface with microphase separated structure controlled capping formation of platelet owing to affecting the dynamic motion of platelet membrane.
